<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<script>
  let p = new Promise((resolve, reject)=>{

    try {
      console.log('正在申请查询A的数据..........')
      throw new Error('A的数据查询失败')
      setTimeout(()=>{
        console.log('A的数据查询完成!!!')
        resolve()
      },2000)
    }catch (e){
      reject(e.message)
    }
  })
  p.then(value => {})
  p.catch(reason => {
    return new Promise((resolve, reject)=>{
      console.log(reason+'3秒后讲帮您查询C数据')
      setTimeout(()=>{
        console.log('C数据查询完成')
      },3000)
    })
  })
  .then(value => {
    console.log(value)
  })


</script>
</body>
</html>